Feedback divider for fluid amplifier



R. w. WARREN FEEDBACK DIVIDER FOR FLUID AMPLIFIER Aug. 20, 1968 Filed Sept. 10, 1962 Z mm V WW. W w W W United States Patent O 3 397 713 FEEDBACK DIVIDEK FR FLUID AMPLIFIER Raymond W. Warren, McLean, Va., assignor to the United tates of America as represented by the Secretary of the rmy Filed Sept. 10, 1962, Ser. No. 222,748 9 Claims. (Cl. 137-815) The invention described herein may be manufactured and used by or for the Government of the United States of America for governm'ental purposes without the payment of any royalty thereon.

This invention relates to fiuid amplifiers and, more particularly, to feedback dividers in fiuid amplifiers.

In previous fluid amplifiers, the dividers which separate the output channels Were substantially wedge shaped with the pointed edge of the wedge aligned with the power nozzle in such a manner that the divider would separate the interaction region into two output channels. If all of the flow from the power stream could not be contained in one output channel, the divider Would separate the power stream into a majority flow and a minority fiow into the output Channels. The favored channel was the channel which had the majority of the power stream flow. Favoring of one output channel over the other was a function of the symmetry of the amplifier elements, the smoothness of the surfaces exposed to the power stream flow, the divergence of the output Channels, the amount of control provided directly on the stream, boundary layer effects, loading of the outputs, and the like. Once favored, the power stream would remain in the favored output channel until a control signal was provided to switch it to the other channel. This control signal could originate externally of the amplifier, could be a portion of the power stream fed back to the interaction Chamber from a location downstream from the divider, or the like.

In some fiuid amplifiers, such as bistable devices, it is desired that the stream remain in one output channel a -prescribed length of time. There are various causes for instability that would prevent the stream from remaining in a favored channel until switching to the other channel is desired. One of these causes is encountered when the amplifier is connected to a load. The resistance in the system could be such that the output channel would no longer carry all of the power stream as it would in an unloaded condition. Under these circumstances, the return of the excess power stream down the favored channel against the flow of the power stream can cause perturbations and turbulences that would promote instability. Since all the fiuid does not get out into the load, some of the fiuid leaks around the divider and out through the other channel. Oscillations as well as other instabilities may result. Further, the direction of all of the power stream into a favored output channel and maintaining it there could require an excessive amount of control signal, and could require that the control signal be applied for an excessive amount of time.

Accordingly, this invention is directed to improvements in fiuid amplifier dividers which provide: increased stability in a fiuid amplifier; reliability of memory functions; an assist to the boundary layer lock-on phenomena; the reduction or elimination of counter flow through the unfavored output channel as well as the need therefor; momentum in a feedback flow which serves as a locking control signal; feedback signals which have vector properties, and feedback signals which operate in the manner of a servo feedback signal.

It is, therefore, an object of this invention to provide an improved divider in a fluid-operated device.

A further object of this invention is to provide a divider which contributes to the stability of a fiuid amplifier.

A still further object of this invention is to provide a 3,397,713 Patented Aug. 20, 1968 "ice divider which enables reliability of memory functions in a fiuid amplifier.

Another object of this invention is to provide a divider which contributes assistance to the boundary layer lockon phenomena by means of feedback.

Still another object of this invention is to provide a divider in a bistable fiuid-operated device which reduces the counterflow in the output channel not favored by the power stream.

A further object of this invention is to provide a divider which eliminates the need of counterflow in the output channel not favored by the power stream in a fluid amplifier so as to enable the use of the fiuid amplifier in outer space or other low pressures environments.

A still further object of this invention is to provide a divider in a fiuid amplifier which provides a momentum in a feedback flow which serves as a control signal.

Another object of this invention is to provide a divider in a fiuid amplifier through which a portion of the power stream is fed back as an auxiliary signal having vector properties which are utilized to reinforce the favoring of an output channel by the power stream.

Still another object of this invention is to provide a divider in a fiuid amplifier with a feedback channel therethrough which eliminates the counterflow around the pointed edge of the divider that previously caused instability.

A further object is to provide a servo operation in a bistable fiuid amplifier.

FIGURE 1 shows a first embodiment of this invention.

FIGURE 2 shows a second embodiment of the invention of this disclosure.

FIGURE 3 shows a third embodiment of the invention of this disclosure.

Briefiy, the purposes of this invention are accomplished by the provision of a divider in a fiuid amplifier which has a means for feeding a part of the power stream in one receiver back to reinforce the forces diverting the power stream into the one receiver. This feedback is through the splitter, in some examples, and down the other receiver to further divert the power stream. In other examples, the feedback is against a blunted or curved end of the divider to provide a pressure seal over the entrance to the not favored output channel and also to reinforce the diverting forces on the power stream which direct it into the favored channel. A Vortex is generated to further enhance the reinforcement.

Turning now to the drawings, FIGURE 1 shows a first modification of a fiuid amplifier constructed in accordance with the principles of this invention. Securing means 9, such as screw means or the like, hold the three plates 11, 12 and 13 in such a manner that the fluid is confined within Channels in the center plate 11. The channels in plate 11 are either molded, machined, carved, etched, printed or are provided by any other method consistent with channeling the material employed. The material can be lucite, plexiglass, metal, glass or any other fluid confining material having proper rigidness, proper capability of being channeled and having chemical inertance to the fiuids employed. The fiuids can be air, water, or any of many gasses and liquids.

Bottom plate 12 is a continuous piece of material without any openings therein. Top plate 13 has openings therein for the entry of the power fiuid and the control fluids. A divider 14 is provided with a channel 15 therethrough. Channel 15 is positioned downstream from the pointed end of divider 14 perpendicular to the long axis of the wedge shaped divider 14. The fiuid power source is connected to the fiuid amplifier through the top plate 13, channel and power nozzle unit 16 and is directed generally toward the point of divider 14 or toward a side thereof depending upon the memory requirements. Control fluids enter the fluid amplifier through the top plate 13, left control channel and nozzle unit 17 and through top plate 13, right control channel and nozzle unit 18. The left and right control nozzles are directed toward each other and are perpendicular to the power stream nozzle unit 16. The three nozzles issue fiuid into an interaction Chamber 19 which is bounded by divider 14 and a pair of divergent sidewalls which are the outer boundaries of output Channels, or receivers, 21 and 22. Interaction chamber 19' is also bordered by the wall that defines the dstance that the control nozzles are set back from the power nozzle. The inner Iboundaries of out-put lreceivers 21 and 22 are the sides of the divider 14 which diverge from the pointed edge. Constrictive means 23 are shown in receivers 21 and 22 far downstream to syrnbolize the impedance otfered to the power stream when a load is introduced into the system. The receivers 21 and 22 are open to the atmosphere, or outer space when applicable, as shown, or can be directed to a load device, or to a sump.

-`In the 'modification shown in FIGURE 2, structural difference from FIGURE 1 is found in the curvature of the channel 31 through the divider as opposed to the straight channel 15 of FIGURE 1. The curvature of channel 31 is directed so as to receive a portion of the power stream in one receiver and direct such portion through the other receiver toward the power stream in such a way as to ntroduce vector properties to the portion fed back. Channel 31 is concave in shape when viewed from the pointed end of the divider.

In the :modification shown in FIGURE 3, a curved surface 41 of the divider has the same concavity as the channel 31 in FIGURE 2. All of the downstream material of the vdivider has 'been removed to present the surface 41 as the Curved leading edge of the divider between output receivers 42 and 43. Between the curved surface 41 and the interaction chamber 47, there is no divider structure. The curved structure 41 is concave when viewed from the power nozzle. The interaction Chamber 47 is bounded by the divider 41, a pair of divergent sidewalls which are the outer boundaries of output receivers 42 and 43 and the wall that defines the distance that the control nozzles are set back from the power nozzle. The power nozzle and the control nozzles are directed into the interaction chamber 47 of FIGURE 3 in the same manner as the power and control nozzles are directed into interaction chamber 19 in FIGURE 1.

In the operation of the feedback divider as illustrated in FIGURE 1, once the power stream has favored one of the output receivers 21 or 22, the feedback channel 15 in divider 14 receives that 'portion of the power stream that the output receiver does not transmit to the load. The fiow through the feedback channel 15 is provided by the excess fiow in the favored receiver. This excess fiow may be in the form of a counterfiow that is created when the load, -due to impedance, is incapable of accepting all of the power stream. The operation of the feedback splitter shown in FIGURE 1 with the dotted areas representin'g the power stream and the fiuid fed through the channel 15 in the divider 14. The arrows in the right receiver 21 indicates the fiow path of the power stream shown that has favored the right receiver. Upon arriving at the impedance means 23, the power stream is separated into fiow through the opening in the impedance means 23 and into the counterfiow back toward the interaction chamber. The channel 15 in the divider receives this counterfiow and directs it into the unfavored receiver 22 of the illustration. Some of the feedback fiuid flows toward the interaction chamber 19 and is entrained by the power stream. This feedback path prevents the disturbance of the power stream in the vicinity of the greatest lock-on pressure which would have been caused had the counterfiow traveled around the pointed end of the divider as is the case with a divider that has no feedback provision. Since there is no counterfiow down the unfavored receiver 22 from external sources, a portion of the feedback flow is free to drift outward, toward the load. With the reinforcement given by the feedback -flow and the absence of counterfiow around the divider, the power stream will be more stable and will remain in a receiver until a control signal is supplied through the appropriate control nozzle. When the power stream is in receiver 21, as shown in FIGURE l, a control signal through channel and control nozzle unit 18 would cause the power stream to shift to the vleft receiver 22.

In the operation of the modification shown in FIG- URE 2, the cur-ved channel 31 through the divider provides the feedback fiow in the unfavored receiver 33 with the vector property of direction. This direction is, generally, toward the power stream in the interaction chamber to -reinforce the lock-on and assure the stability of the power stream in the favored receiver. The entrainment of the feedback fiow into the power stream redirects the feedback fiuid to complete the feedback loop. As in FIG- URE 1, the absence of counterfiow down the unfavored receiver allows a portion of the feedback fiow to be directed outwardly toward the load.

In the operation of the modification shown in FIGURE 3, the divider Curved edge 41 directs the feedback fiow down the unfavored receiver sidewall into the interaction chamber 47. The fiow that is adjacent the divider 41 is directed in a path that approaches the receiver sidewall, and in the vicinity of the sidewall, turns to travel near the sidewall in a direction away from the interaction chamber 47 as shown by flow line 44. A majority of the feedback flow is directed into the interaction chamber where a Vortex 45 is formed 1by the curved fiow of the feedback fiuid to provide momentum to the power stream in receiver 42 to further lock the power stream therein. The remainder of the flow distributes through the remainder of the interaction chamber 47 in the circular paths indicated by the remaining arrows 46.

The fiow line 44 indicates a pressure area which is a barrier sufficient to maintain 'power stream integrity even if the pressure available exterior to the fluid amplifier is very low. This permits the amplifier to operate in outer space. The Vortex 45 and the lock-on assist vectors 46 would be maintained in the absence of 'a counter pressure down the unfavored receiver 43.

The fiuid 'amplifiers in this disclosure are the wall-effect type. The action of the feedback divider is to assist the basic bistable performance of these wall-effect amplifiers. The basic bistability comes about because the stream entrains away fiuid 'and produces a low-.pressure separation bubble on the wall. This is indicated in the drawings by the exposure of the short |b-ottom end of the sidewall of the favored receiver to which the power stream is shown not attached. The entrainment and the bubble provide a low-pressure region which allows the higher pressure on the opposite side of the power stream to hold the stream against the favored sidewall. The elfectiveness of the holding of the stream 'against the sidewall depends on the pressure differential on the two sides of the stream. The 'feedback divider splits olf part of the stream and directs it so as to increase the pushing pressure lock-on. In the modification shown in FIGURE 3, should the stream 'move away from the bistable position, more of the stream is split off and the pushing pressure is increased forcing the stream back into its bistable position. The action of this restoring pressure that is generated is similar to the action of a servo loop.

When the .power stream is in the left receiver, such as receiver 22 in FIG. 1, the feedback through channel 15 in divider 14 is in a reverse direction from that when the power stream is in right receiver 21.

Fluid amplifiers of the type -of which this invention is an improvement are more adequately disclosed in the copending application entitled Fluid Amplifier Employing Boundary Layer Effect, Ser. No. 58,'188, filed Oct. 19, 1960 by Raymond W. Warren et al.

So, it is seen that we have provided an mproved divider in a fiuid amplifier. The divider improvements of this discl-osure contribute to stability 'and enable reliability of memory functions in a fiuid amplifier, The counterflow in the not-favored output channel is reduced or elimin'ated and operation in outer space is provided. The lock-on phenomenon is reinforced -by the feedback fiow and by the momentum of such flow. The feedback fiow has vector properties. The counter-flow around the pointed edge of the divider has been eliminated and the Wandering of the power stream |has been used to provide 'a pressure lproportional to such wandering to reinforce the power stream in a stable position in the manner of a servo loop.

It will be apparent that the embodiment shown is only exemplary and that various modific'ations can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

The divider 41 in 'FIGURE 3 can ibe concave as shown, blunted as said above, squ'ared off, or in any Shape that will provide the fiow pattern needed to reinf'orce the lockon pressure differential and provide stability. An example of such a flow pattern is shown in FIGURE 3 by arrows 46 and Vortex 45. Dividers shaped like a flat open box, with the open end directed toward the power stream, will provide a fiow pattern that is equivalent t-o that provided by a concave divider.

I claim as my invention:

1. In a fiuid 'amplifier:

(a) means for producing a fiuid power stream,

(b) a pair of receiver means for receiving said power stream,

(c) divider means for separating said pair of receiver means, and

(d) feedback means connecting said pair of receiver means through said divider means.

2. In a fiuid amplifier:

(a) a fiuid power source,

(b) a pair of receiver means,

(c) means for directing said fluid toward said pair of receiver means, and

(d) divider means for separating said pair of receiver means,

(e) said divider means providing a feedback fiow of a portion of said power stream to stabilize said power stream in one of said receiver means.

3. In a fiuid amplifier:

(a) a fiuid power source for producing a fluid stream,

(b) a pair of receiver means,

(c) means for directing sa-id fiuid stream toward said pair of receiver means,

(d) divider means for separating said pair of receiver means, and

(e) channel means through said divider means for providing a feedback fiow,

(f) said channel means connecting one receiver means to the other receiver means.

4. In a fiuid amplifier:

(a) a fiuid power source for producing a fiuid stream,

(b) a pair of receiver means,

(c) means for directing said fiuid stream toward said pair of receiver means,

(d) divider means for separating said pair of receiver means,

(e) channel means having substantially parallel walls through said divider means,

(f) said channel means providing a feedback fl0w,and

(g) said chanel means connecting one receiver means to the other receiver means.

5. In a fiuid amplifier:

(a) a fiuid power source for producing a fiuid stream,

(b) a pair of receiver means,

(c) means for directing said fiuid stream toward said pair of receiver means,

(d) divider' means for separating said pair of receiver means,

(e) channel means having substantially parallel walls through said divider means,

(f) said channel means providing a feedback fiow, 'and (g) said channel means connecting one receiver means to the other receiver means substantially perpendicular to the direction of said power stream flow.

6. In a fiuid amplifier:

(a) a fiuid power source 'for producing a fiuid stream,

(b) a pair of receiver means,

(c) means for directing said fluid stream toward said pair of receiver means,

(d) divider means for separating said pair of receiver means,

(e) arcuate channel means through said divider means,

(f) said channel means providing a feedback fiow, and

(g) said channel means connecting one receiver means to the other receiver means.

7. In a fiuid amplifier:

(a) a fiuid power source for producing a fiuid stream,

(b) a pair of divergent receiver means,

(c) means for directing said fiuid stream toward said pair of receiver means,

(d) divider mean-s for separating said pair of receiver means,

(e) arcuate channel means through said divider means,

(f) said channel means providing a feedback fiow,

(g) said channel means connecting one receiver means to the other receiver means,

(h) the curvature of said channel means being concave with respect to the power stream source, and

(i) said channel means being located downstream from the point of convergence of the divider means for -separating said pair of divergent receiver means.

8. In a fiuid amplifier:

(a) means for providing a fiuid power stream,

(b) first and second means for receiving said power stream,

(c) means for separating said first and second means 'for receiving said power stream,

(d) said means for separating including means for feeding back a portion of said power stream to reinforce said power stream in one of said means for receiving,

(e) said means for feeding back providing increased reinforcement when said power stream tends to move to the other of said means for receiving said power stream.

9. In a pure fiuid amplifier of the type including a power stream, an interaction chamber and a divider element positioned in said chamber for separating two output channels therefrom, the improvement which comprises the inclusion of an aperture in said divider element for fiuid communication between said output channels in order to limit excessive backpressure in at least one of said channels.

References Cited UNITED STATES PATENTS 1,658,797 2/1928 Charette et al 230--92 3,030,979 4/1962 Reilly 137-83 X 1,381,095 6/1921 Starr 239-468 X 2,893,432 7/1959 Gibson 138-42 X 3,075,227 1/1963 Bowles 15-346 FOREIGN PATENTS 1,278,781 11/1961 France.

254,020 6/ 1926 Great Britain.

SAMUEL SCOTT, Primary Examner. 

1. IN A FLUID AMPLIFIER: (A) MEANS FOR PRODUCING A FLUID POWER STREAM, (B) A PAIR OF RECEIVER MEANS FOR RECEIVING SAID POWER STREAM, (C) DIVIDER MEANS FOR SEPARATING SAID PAIR OF RECEIVER MEANS, AND 